Polyols are widely used for paint, adhesive, elastomer etc. in combination with a curing agent which reacts with hydroxyl group. The polyols generally include polyether polyol such as polypropylene glycol and polytetramethylene glycol; polyester polyol obtained by reacting polyvalent carboxylic acid and polyhydric alcohol; polylactone polyol obtained by reacting lactone with alcohol; poly(meth)acrylate polyol obtained by polymerizing (meth)acrylate having a hydroxyl group such as 2-hydroxyethyl methacrylate. They are selectively used for various applications according to the required performances.
However, since polyether polyol has ether bonds, the paint film obtained using it has the drawback of being inferior in heat stability and weather stability. Also, since polyester polyol and polylactone polyol has ester bonds, the paint film obtained from them has the drawback of being inferior in water resistance. Further, poly(meth)acrylate polyol has good weather stability but it has the drawback of being poor in dynamic property.
In order to obtain the paint film free from such drawbacks, it is proposed to use polycarbonate polyol having carbonate bond in the molecular structure. For example, Japanese Kokai Publication 45522/1990 discloses a coating composition which comprises (1) a polycarbonate polyol obtained from a saturated aliphatic .alpha.,.omega.-glycol having 4 to 12 carbon atoms and tris-(hydroxyethyl)-isocyanurate and (2) a melamine resin or isocyanate curing agent.
However, since the saturated .alpha.,.omega.-glycol has high crystallinity, the obtained polycarbonate polyol has crystallinity. Consequently, the paint composition described in the aforesaid publication has poor solubility with Usual solvent and poor compatibility with the curing agent. The inferior compatibility with curing agent causes poor curing ability and poor appearance of the paint film, and results in the decline of durability and physical property of the paint film.